North Korea has been pursuing a missile programme since the 1970s, eventually concluding that a nuclear deterrent was needed to ensure the survival of its dynastic regime. In recent months, however, it has adopted a more diplomatic approach.

After years of fraught relations with the United States and regional neighbours over its nuclear missile programme, North Korea ratcheted up tensions late last year with a series of missile launches over Japan and the announcement in November that its intercontinental ballistic missile (ICBM) capability now had the entire United States within range.

Within months, however, North Korean leader Kim Jong-un appeared to change tack, offering direct talks with both South Korea and the United States, and meeting for the first time with Chinese President Xi Jinping, to whom he pledged a commitment to denuclearisation. The new diplomatic push will culminate with a bilateral June 12 meeting with US President Donald Trump in Singapore.

Below are some of the key dates in North Korea's quest to develop a nuclear weapons capability and its recent shift toward pursuing diplomacy.

Late 1970s: North Korea begins working on its own version of the Scud missile with a range of 300 kilometres (185 miles). It is test-fired for the first time in 1984.

April 5, 2009: North Korea launches a long-range rocket that flies over Japan and lands in the Pacific in what it again says is an attempt to put a satellite into orbit. The United States, Japan and South Korea say the launch was actually the test of a Taepodong-2 missile.

May 25, 2009: Pyongyang conducts its second underground nuclear test, several times more powerful than the first.

December 12, 2012: A multi-stage rocket successfully places an observational satellite into orbit.

February 12, 2013: North Korea conducts a third underground nuclear test.

January 6, 2016: A fourth underground nuclear test is carried out that North Korea says was a hydrogen bomb, a claim doubted by most experts.

March 6, 2017: North Korea fires four ballistic missiles in what it says is an exercise aimed at striking US military bases in Japan. The next day the US begins deploying its THAAD missile defence system in South Korea.

May 2, 2017: The United States announces that its THAAD missile defence system is now "operational" in South Korea.

May 14, 2017: North Korea fires a ballistic missile that flies 700 km before landing in the Sea of Japan. Analysts say it has a theoretical range of 4,500 kilometres (2,800 miles) and brings the US territory of Guam within reach.

July 4, 2017: Pyongyang test-fires a ballistic missile that analysts say brings Alaska into range. North Korean state media call it a "landmark" test of a Hwasong-14 intercontinental ballistic missile.

July 28, 2017: North Korea launches an ICBM with a theoretical range of 10,000 kilometres, meaning it could hit much of the continental United States.

August 29, 2017: North Korea fires a ballistic missile over Japan, prompting the government of Prime Minister Shinzo Abe to warn people to take cover in an incident he called an "unprecedented, serious and grave threat".

September 3, 2017:Pyongyang carries out its sixth and most powerful nuclear test to date, generating a 6.3-magnitude earthquake. Japanese analysts estimated the device's explosive yield at 160 kilotons, making it 10 times more powerful than the bomb dropped on Hiroshima during World War II. Pyongyang also claims it has developed a miniaturised H-bomb that can be loaded onto a missile.

September 15, 2017:North Korea fires another ballistic missile over Japan and into the Pacific in what appears to be its furthest-ever missile flight. Millions of Japanese were awoken by sirens and emergency text message alerts. The UN Security Council condemns the launch as "highly provocative".

November 28, 2017: North Korea announces the successful launch of a Hwasong-15 ICBM, which Pyongyang says now puts all of the US mainland in its missile range.

December 22, 2017: The UN Security Council unanimously votes to impose new sanctions on North Korea’s economy following its latest missile test, limiting its oil imports and demanding the repatriation of North Koreans working abroad.

December 24, 2017: Pyongyang slams the new UN sanctions as “an act of war”.

February 9, 2018: Kim Jong-un's sister attends the Winter Olympics in South Korea, becoming the first member of the ruling family to set foot in the South since the Korean War.

March 6, 2018: North Korea agrees to a possible summit with South Korea and a possible nuclear freeze, saying it would consider abandoning its nuclear programme in exchange for security guarantees.

March 8, 2018: Trump accepts an invitation from Kim Jong-un for direct talks.

March 28, 2018: Kim makes his first-ever official trip to meet China's President Xi Jinping, saying he is "committed to denuclearisation" and expressing his willingness to hold summits with both South Korea and the United States.

April 21, 2018: Kim says North Korea no longer needs to conduct nuclear or missile tests because it has achieved its goal of developing nuclear weapons, according to the state-run Korean Central News Agency (KCNA). "We will concentrate all efforts on building a powerful socialist economy and markedly improving the standard of people's living,” KCNA reported him as saying.

Some scientists surmise that the September collapse of North Korea's nuclear test site, which may have rendered it inoperative, was behind Kim's announcement rather than any change of heart.

May 24, 2018: North Korea dismantles its Punggye-ri nuclear test site in a goodwill gesture ahead of a summit with the United States, inviting foreign journalists to witness the demolition. Analysts remain divided over whether the destruction actually renders the test site inert, however.

June 12, 2018: A historic face-to-face between the North Korean and US leaders is scheduled to take place in Singapore. Besides negotiations over Pyongyang's nuclear missile programme, the highly anticipated talks are also likely to focus on economic sanctions against North Korea and the larger situation on the Korean Peninsula, where the two sides officially remain at war.